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JavaScript Asynchronous Programming with JavaScript Asynchronous JavaScript with Callbacks Implement a Callback

Posted by Agata Zurek
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Agata Zurek
Full Stack JavaScript Techdegree Graduate 26,419 Points

How does generateHTML get its argument passed to it?

Could someone please explain how generateHTML "knows" what its argument is? Thanks!!

1 Answer

Axel Perossa
Axel Perossa
13,930 Points

You pass a reference of generateHTML to the getJSON function:

getJSON(wikiUrl + person.name, generateHTML);

In the getJSON function, that reference to generateHTML is stored in the callback parameter (check the function definition of getJSON in the code).

The getJSON function will later call generateHTML in the line

return callback(data);

so that line is the same as doing generateHTML(data). That's the exact moment where you pass the info to generateHTML so it can do its thing.

Agata Zurek
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Agata Zurek
Full Stack JavaScript Techdegree Graduate 26,419 Points

Thank you! That really helps.